Optimization Of Mild Chamber For The Combustion Of Biomass Producer Gas
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Date
2022-07-24
Authors
Moustafa Hebish, Anas Ahmed Moustafa Moustafa
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Energy production still heavily relies on combustion. MILD combustion is a
promising candidate to support the transition towards the net zero emission target,
however it needs further fundamental study due to the current limited research on its
application on low-grade biomass producer gas (PG). The main challenge is to achieve
complete combustion in MILD combustion with low CO and NOx emissions while
maintaining simple and compact combustor geometry. The aim of this study was to
tackle the challenges of low-grade biomass producer gas (PG) through optimization of
MILD combustion. The work included using ANSYS-FLUENT computational fluid
dynamics (CFD) simulation of low-grade biomass producer gas (PG) from wood air-gasification in a MILD combustion chamber. The study included two stages of Design
of Experiments (DOE), first-stage (DOE1) and second-stage (DOE2). Geometry
parameters, for two shapes (circular cross-section and square cross-section combustors)
were tested by using 18 CFD simulation cases and results were analysed through DOE1
optimization tool. Optimum geometry for circular combustors was 200mm in
combustor diameter, Dc and 1000mm in combustor length, Lc with 710°C maximum
temperature increase, 3.3 ppm CO emissions, 15.2 ppm NOx emissions and 0.99
Damköhler number and the optimum geometry for square combustors was 548.86mm
combustor length, Ls and 1500mm combustor height, Hs with 718°C maximum
temperature increase, 6.41 ppm CO emissions, 342.24 ppm NOx emissions and 0.34
Damköhler number. The circular combustors significantly surpassed the square ones in,
terms of performance, for CO and NOx emission and Damköhler number with the
exception of maximum temperature increase. DOE2 involved the optimum circular
combustor since circular combustors generally outperformed the square combustors
and had better optimum combustor characteristics. DOE2 had 9 CFD simulations based
on the instruction of DOE. DOE2 aimed to optimize the MILD combustion chamber for
operating conditions. In the end , the circular cross-section combustor of 200mm in
combustor diameter, Dc and 1000mm in combustor length, Lc with fuel-air equivalence
ratio, φ = 0.9 and fuel inlet velocity, Vf = 200m/s having 733°C maximum temperature
increase, 2.5 ppm CO emissions, 11.1 ppm NOx emissions and 0.76 Damköhler number
was considered the optimum MILD chamber .